Terminal apparatus, base station apparatus, communication method, and integrated circuit

ABSTRACT

A terminal apparatus for communicating with a base station apparatus receives an RRC connection reconfiguration request message including a Data Radio Bearer (DRB) configuration from the base station apparatus. The DRB configuration includes a DRB identity and an SDAP entity configuration corresponding to the DRB identity. The SDAP entity configuration includes an SDAP header length. An SDAP entity is established in accordance with SDAP configuration information in which the SDAP header length is one or more of integer values of a multiple of eight including zero.

TECHNICAL FIELD

The present invention relates to a terminal apparatus, a base stationapparatus, a communication method, and an integrated circuit.

BACKGROUND ART

A radio access method and a radio network (hereinafter, referred to as“Long Term Evolution (LTE: Registered Trademark)” or “Evolved UniversalTerrestrial Radio Access (EUTRA)”), and a core network (hereinafter,“Evolved Packet Core (EPC)”) for cellular mobile communications havebeen studied in the 3rd Generation Partnership Project (3GPP).

Furthermore, as a radio access method and a radio access networktechnology for a fifth-generation cellular system, a technical study andstandardization of LTE-Advanced Pro which is an enhanced technology ofthe LTE, and New Radio Technology (NR) which is a new radio accesstechnology have been conducted by the 3GPP (NPL 1). Additionally 5Generation Core Network (5GC), which is a core network for a fifthgeneration cellular system, has also been studied (NPL 2).

CITATION LIST Non Patent Literature

NPL 1: 3GPP RP-170855, “Work Item on New Radio (NR) Access Technology”

NPL 2: 3GPP TS 23.501, “System Architecture for the 5G System; Stage 2”

NPL 3: 3GPP TS 36.300, “Evolved Universal Terrestrial Radio Access(E-UTRA) and Evolved Universal Terrestrial Radio Access Network(E-UTRAN); Overall description; Stage 2”

NPL 4: 3GPP TS 36.331, “Evolved Universal Terrestrial Radio Access(E-UTRA); Radio Resource Control (RRC); Protocol specifications”

NPL 5: 3GPP TS 36.323, “Evolved Universal Terrestrial Radio Access(E-UTRA); Packet Data Convergence Protocol (PDCP) specification”

NPL 6: 3GPP TS 36.322, “Evolved Universal Terrestrial Radio Access(E-UTRA); Radio Link Control (RLC) protocol specification”

NPL 7: 3GPP TS 36.321, “Evolved Universal Terrestrial Radio Access(E-UTRA); Medium Access Control (MAC) protocol specification”

NPL 8: 3GPP TS 37.340, “Evolved Universal Terrestrial Radio Access(E-UTRA) and NR; Multi-Connectivity; Stage 2”

NPL 9: 3GPP TS 38.300, “NR; NR and NG-RAN Overall description; Stage 2”

NPL 10: 3GPP TS 38.331, “NR; Radio Resource Control (RRC); Protocolspecifications”

NPL 11: 3GPP TS 38.323, “NR; Packet Data Convergence Protocol (PDCP)specification”

NPL 12: 3GPP TS 38.322, “NR; Radio Link Control (RLC) protocolspecification”

NPL 13: 3GPP TS 38.321, “NR; Medium Access Control (MAC) protocolspecification”

NPL 14: 3GPP TS 23.401 v14.3.0, “General Packet Radio Service (GPRS)enhancements for Evolved Universal Terrestrial Radio Access Network(E-UTRAN) access”

SUMMARY OF INVENTION Technical Problem

As one technical study on NR, a system called Multi-RAT DualConnectivity (MR-DC) has been studied that allows cells of Radio AccessTechnologies (RATs) of both E-UTRA and NR to be grouped for each RAT andto be allocated for a UE such that a terminal apparatus communicateswith one or more base station apparatuses (NPL 8).

However, since the formats and functions of the communication protocolsused in E-UTRA and NR differ, there is a problem in that protocolprocessing becomes complicated compared to Dual Connectivity inconventional LTE using only E-UTRA as a RAT, and thus a base stationapparatus and a terminal apparatus are not able to efficientlycommunicate with each other.

In view of the circumstances described above, an object of an aspect ofthe present invention is to provide a terminal apparatus capable ofefficiently communicating with a base station apparatus, a base stationapparatus communicating with the terminal apparatus, a communicationmethod used for the terminal apparatus, a communication method used forthe base station apparatus, an integrated circuit mounted on theterminal apparatus, and an integrated circuit mounted on the basestation apparatus.

Solution to Problem

In order to accomplish the object described above, an aspect of thepresent invention is contrived to provide the following measures. Thatis, an aspect of the present invention is a terminal apparatus thatsupports EN-DC. The terminal apparatus includes a receiver configured toreceive an RRC connection reconfiguration message from a base stationapparatus. The RRC connection reconfiguration message includes a radiobearer identity. The terminal apparatus further includes a configurationunit configured to establish a PDCP entity in accordance with a PDCPentity configuration for NR in a case that the terminal apparatus hasnot configured a value of the radio bearer identity and in a case thatthe RRC connection reconfiguration message includes the PDCP entityconfiguration for NR.

Additionally, an aspect of the present invention is a terminal apparatusthat supports EN-DC. The terminal apparatus includes a receiverconfigured to receive an RRC connection reconfiguration message from abase station apparatus. The RRC connection reconfiguration messageincludes a radio bearer identity and a PDCP entity configurationcorresponding to the radio bearer identity. The PDCP entityconfiguration is either the PDCP entity configuration for E-UTRA or thePDCP entity configuration for NR. The terminal apparatus furtherincludes a configuration unit configured to establish a PDCP entity inaccordance with the PDCP entity configuration for NR in a case that theterminal apparatus has not configured a value of the radio beareridentity and in a case that the RRC connection reconfiguration messagedoes not include the PDCP entity configuration for E-UTRA.

Additionally, an aspect of the present invention is a base stationapparatus that supports EN-DC. The base station apparatus includes ageneration unit configured to generate an RRC connection reconfigurationmessage and a transmitter configured to transmit the RRC connectionreconfiguration message to a terminal apparatus. The RRC connectionreconfiguration message includes a radio bearer identity. The RRCconnection reconfiguration message including the radio bearer identitycauses the terminal apparatus to establish a PDCP entity in accordancewith a PDCP entity configuration for NR in a case that the terminalapparatus has not configured a value of the radio bearer identity and ina case that the RRC connection reconfiguration message includes the PDCPentity configuration for NR.

Additionally, an aspect of the present invention is a base stationapparatus that supports EN-DC. The base station apparatus includes ageneration unit configured to generate an RRC connection reconfigurationmessage and a transmitter configured to transmit the RRC connectionreconfiguration message to a terminal apparatus. The RRC connectionreconfiguration message includes a radio bearer identity and a PDCPentity configuration corresponding to the radio bearer identity. ThePDCP entity configuration is selected from the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. The RRC connectionreconfiguration message including the radio bearer identity and the PDCPentity configuration causes the terminal apparatus to establish a PDCPentity in accordance with the PDCP entity configuration for NR in a casethat the terminal apparatus has not configured a value of the radiobearer identity and in a case that the RRC connection reconfigurationmessage does not include the PDCP entity configuration for E-UTRA.

Additionally, an aspect of the present invention is a method performedby a terminal apparatus that supports EN-DC, the method including thestep of receiving an RRC connection reconfiguration message from a basestation apparatus. The RRC connection reconfiguration message includes aradio bearer identity. A PDCP entity is established in accordance with aPDCP entity configuration for NR in a case that the terminal apparatushas not configured a value of the radio bearer identity and in a casethat the RRC connection reconfiguration message includes the PDCP entityconfiguration for NR.

Additionally, an aspect of the present invention is a method performedby a terminal apparatus that supports EN-DC. The method includes thestep of receiving an RRC connection reconfiguration message from a basestation apparatus. The RRC connection reconfiguration message includes aradio bearer identity and a PDCP entity configuration corresponding tothe radio bearer identity. The PDCP entity configuration is either thePDCP entity configuration for E-UTRA or the PDCP entity configurationfor NR. A PDCP entity is established in accordance with the PDCP entityconfiguration for NR in a case that the terminal apparatus has notconfigured a value of the radio bearer identity and in a case that theRRC connection reconfiguration message does not include the PDCP entityconfiguration for E-UTRA.

Additionally, an aspect of the present invention is a method performedby a base station apparatus that supports EN-DC. The method includes thesteps of: generating an RRC connection reconfiguration message; andtransmitting the RRC connection reconfiguration message to a terminalapparatus. The RRC connection reconfiguration message includes a radiobearer identity. The RRC connection reconfiguration message includingthe radio bearer identity causes the terminal apparatus to establish aPDCP entity in accordance with a PDCP entity configuration for NR in acase that the terminal apparatus has not configured a value of the radiobearer identity and in a case that the RRC connection reconfigurationmessage includes the PDCP entity configuration for NR.

Additionally, an aspect of the present invention is a method performedby a base station apparatus that supports EN-DC. The method includes thesteps of: generating an RRC connection reconfiguration message; andtransmitting the RRC connection reconfiguration message to a terminalapparatus. The RRC connection reconfiguration message includes a radiobearer identity and a PDCP entity configuration corresponding to theradio bearer identity. The PDCP entity configuration is selected fromthe PDCP entity configuration for E-UTRA and the PDCP entityconfiguration for NR. The RRC connection reconfiguration messageincluding the radio bearer identity and the PDCP entity configurationcauses the terminal apparatus to establish a PDCP entity in accordancewith the PDCP entity configuration for NR in a case that the terminalapparatus has not configured a value of the radio bearer identity and ina case that the RRC connection reconfiguration message does not includethe PDCP entity configuration for E-UTRA.

Advantageous Effects of Invention

According to an aspect of the present invention, the terminal apparatusand the base station apparatus can lower complexity of protocolprocessing and communicate efficiently.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a communication system according toeach embodiment of the present invention.

FIG. 2 is a protocol stack diagram of a UP and a CP of a terminalapparatus and a base station apparatus in E-UTRA according to eachembodiment of the present invention.

FIG. 3 is a protocol stack diagram of the UP and the CP of the terminalapparatus and the base station apparatus in NR according to eachembodiment of the present invention.

FIG. 4 is a drawing illustrating an example of a flow of an RRCconnection reconfiguration procedure according to each embodiment of thepresent invention.

FIG. 5 is a block diagram of the terminal apparatus (UE) according toeach embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of DRB configurationreception and configuration according to Embodiment 1 of the presentinvention.

FIG. 7 is a part (first page) of a diagram illustrating an example ofAbstract Syntax Notation One (ASN.1) for a DRB configuration accordingto each embodiment of the present invention.

FIG. 8 is another part (second page) of the diagram illustrating theexample of Abstract Syntax Notation One (ASN.1) for the DRBconfiguration according to each embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of determination of a PDCPconfiguration by a configuration unit of the terminal apparatusaccording to Embodiment 1 of the present invention.

FIG. 10 is a diagram illustrating an example of a relationship betweenradio protocol architecture and RBs in EN-DC on the base stationapparatus side according to Embodiment 2 of the present invention.

FIG. 11 is a diagram illustrating an example of the DRB configurationreception and configuration in a case that an MCG bearer or an SCGbearer is established as a bearer of an anchor cell group according toEmbodiment 2 of the present invention.

FIG. 12 is a diagram illustrating an example of Abstract Syntax NotationOne (ASN.1) for the DRB configuration of an additional cell group in acase that a CG bearer or an SCG bearer is changed to a split beareraccording to Embodiment 2 of the present invention.

FIG. 13 is a diagram illustrating an example of the DRB configurationreception and configuration according to Embodiment 3 of the presentinvention.

FIG. 14 is a diagram illustrating an example of Abstract Syntax NotationOne (ASN.1) for the DRB configuration including SDAP informationaccording to Embodiment 3 of the present invention.

FIG. 15 is a diagram illustrating an example of Abstract Syntax NotationOne (ASN.1) for the DRB configuration including the SDAP informationaccording to Embodiment 3 of the present invention.

FIG. 16 is a part (first page) of a diagram illustrating an example ofAbstract Syntax Notation One (ASN.1) for the DRB configuration accordingto each embodiment of the present invention.

FIG. 17 is another part (second page) of the diagram illustrating theexample of Abstract Syntax Notation One (ASN.1) for the DRBconfiguration according to each embodiment of the present invention.

FIG. 18 is yet another part (third page) of the diagram illustrating theexample of the Abstract Syntax Notation One (ASN.1) for the DRBconfiguration according to each embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below in detailwith reference to the drawings.

LTE (and LTE-A Pro) and NR may be defined as different RATs. The NR maybe defined as a technology included in the LTE. The LTE may be definedas a technology included in the NR. Also, the LTE capable of connectingwith the NR through dual connectivity may be distinguished fromconventional LTE. The present embodiment may be applied to the NR, theLTE and other RATs. Terms associated with the LTE and the NR are used inthe following description. However, the present invention may be appliedto other technologies using other terms.

FIG. 1 is a schematic diagram of a communication system according toeach embodiment of the present embodiment.

An E-UTRA 100 is a radio access technology described in NPL 3 or thelike, and includes a Cell Group (CG) configured in one or more frequencybands. An E-UTRAN Node B (eNB) 102 is an E-UTRA base station apparatus.An Evolved Packet Core (EPC) 104 is a core network described in NPL 14or the like and has been designed as an E-UTRA core network. Aninterface 112 is an interface between the eNB 102 and the EPC 104 inwhich a Control Plane (CP) through which a control signal transfers anda User Plane (UP) through which its user data transfers are present.

An NR 106 is a new radio access technology currently studied in the 3GPPand includes a Cell Group (CG) configured in one or more frequencybands. A gNode B (gNB) 108 is a base station apparatus in the NR. A 5GC110 is a new core network for NR currently studied in the 3GPP, and isdescribed in NPL 2 and the like.

An interface 114 is an interface between the eNB 102 and the 5GC 110, aninterface 116 is an interface between the gNB 108 and the 5GC 110, aninterface 118 is an interface between the gNB 108 and the EPC 104, aninterface 120 is an interface between the eNB 102 and the gNB 108, andan interface 124 is an interface between the EPC 104 and the 5GC 110.The interface 114, the interface 116, the interface 118, the interface120, and the interface 124 are interfaces that transfer CP only, UPonly, or both of the CP and the UP, and details are being discussed bythe 3GPP. The interface 114, the interface 116, the interface 118, theinterface 120, and the interface 124 may not be present depending on acommunication system provided by a carrier.

A UE 122 is a terminal apparatus supporting both the E-UTRA and the NR.

FIG. 2 is a protocol stack diagram of the UP and the CP in the terminalapparatus and the base station apparatus in the E-UTRA according to eachembodiment of the present invention.

FIG. 2(A) is a protocol stack diagram of the UP used in a case that theUE 122 communicates with the eNB 102.

A physical layer (PHY) 200 is a radio physical layer that provides ahigher layer with a transmission service using a Physical Channel. ThePHY 200 is connected to a Medium Access Control layer (MAC) 202 that isa higher layer to be described below via a Transport Channel. Data isexchanged between the MAC 202 and the PHY 200 via the transport channel.The data is transmitted and/or received between the PHYs of the UE 122and the eNB 102 via the radio physical channel.

The MAC 202 maps various Logical Channels to various transport channels.The MAC 202 is connected with a Radio Link Control layer (RLC) 204 thatis a higher layer to be described below via the logical channels. Thelogical channels are roughly classified according to a type oftransmitted information, and classified into control channelstransmitting control information and traffic channels transmitting userinformation. The MAC 202 has a function to control the PHY 200 toperform Discontinuous Reception and Transmission (DRX and DTX), afunction to perform a Random Access procedure, a function to notifytransmit power information, a function to control a HARQ, and the like(NPL 7).

An RLC 204 divides (Segmentation) the data received from a Packet DataConvergence Protocol Layer (PDCP) 206 that is a higher layer to bedescribed later, and adjusts the data size such that a lower layer canproperly transmit the data. The RLC 200 also has a function to ensure aQuality of Service (QoS) requested for each piece of data. In otherwords, the RLC 204 has a function of data retransmission control or thelike (NPL 6).

A PDCP 206 may have a header compression function to compressunnecessary control information to efficiently transmit IP Packets,which is user data, in a radio segment. The PDCP 206 may also have adata encryption function (NPL 5).

Note that data processed in the MAC 202, the RLC 204, and the PDCP 206is referred to as a MAC Protocol Data Unit (PDU), an RLC PDU, and a PDCPPDU, respectively. In addition, data passed from a higher layer to theMAC 202, the RLC 204, and the PDCP 206 is referred to as a MAC ServiceData Unit (SDU), an RLC SDU, and a PDCP SDU, respectively.

FIG. 2(B) is a protocol stack diagram of the CP used in a case that theUE 122 communicates with the eNB 102.

In addition to the PHY 200, the MAC 202, the RLC 204, and the PDCP 206,a Radio Resource Control (RRC) layer 208 is present in the CP protocolstack. The RRC 208 configures and reconfigures Radio Bearers (RBs) tocontrol the logical channels, the transport channels, and the physicalchannels. The RBs may be classified into a Signaling Radio Bearer (SRB)and a Data Radio Bearer (DRB), and the SRB may be used as a path fortransmitting an RRC message as the control information. The DRB may beused as a path for transmitting the user data. Each RB may be configuredbetween the RRCs 208 of the eNB 102 and the UE 122 (NPL 4).

The functional classification of the MAC 202, the RLC 204, the PDCP 206,and the RRC 208 described above is an example, and some or all of therespective functions need not be implemented. Some or all of thefunctions of each layer may be included in another layer.

FIG. 3 is a protocol stack diagram of the UP and the CP in the terminalapparatus and the base station apparatus in the NR according to eachembodiment of the present invention.

FIG. 3(A) is a protocol stack diagram of the UP used in a case that theUE 122 communicates with the gNB 108.

A physical layer (PHY) 300 is a radio physical layer in the NR that mayprovide a higher layer with a transmission service using the PhysicalChannel. The PHY 300 may be connected to a Medium Access Control layer(MAC) 302 that is a higher layer to be described below via the TransportChannel. Data may be exchanged between the MAC 302 and the PHY 300 viathe transport channel. The data may be transmitted and/or receivedbetween the PHYs of the UE 122 and the gNB 108 via the radio physicalchannel. Details of the PHY 300 are different from those of the PHY 200which is the radio physical layer of the E-UTRA, and are being studiedin the 3GPP.

The MAC 302 may map various Logical Channels to various transportchannels. The MAC 302 may be connected with a Radio Link Control layer(RLC) 304 that is a higher layer to be described later via the logicalchannels. The logical channels may be roughly classified according to atype of transmitted information, and may be classified into controlchannels transmitting the control information and traffic channelstransmitting the user information. The MAC 302 may have a function tocontrol the PHY 300 to perform the Discontinuous Reception andTransmission (DRX and DTX), a function to perform the Random Accessprocedure, a function to notify the transmit power information, afunction to control the HARQ, and the like (NPL 13). Details of the MAC302 are different from those of the MAC 202 of the E-UTRA, and are beingdiscussed in the 3GPP.

An RLC 304 may divide (Segmentation) data received from a Packet DataConvergence Protocol Layer (PDCP) 206 that is a higher layer to bedescribed later, and adjust the data size such that a lower layer canproperly transmit the data. The RLC 304 may also have a function toensure Quality of Service (QoS) requested for each piece of data. Inother words, the RLC 304 may have a function of data retransmissioncontrol or the like (NPL 12). Details of the RLC 304 are different fromthose of the RLC 204 in the E-UTRA, and are being discussed in the 3GPP.

A PDCP 306 may have a header compression function of compressingunnecessary control information to efficiently transmit an IP packet,which is the user data, in a radio segment. The PDCP 306 may also have adata encryption function (NPL 11). Details of the PDCP 306 are differentfrom those of the PDCP 206 of the E-UTRA, and are under discussion bythe 3GPP.

A Service Data Adaptation Protocol (SDAP) 310 may function to map QoS ofdata transmitted from the 5GC 110 to the gNB 108 and data transmittedfrom the gNB to the 5GC 110 to QoS of the RB (NPL 9). In a case that theeNB 102 is directly connected to the 5GC 110, that is, connected to the5GC via the interface 114, or in a case that the eNB 102 is indirectlyconnected to the 5GC 110, that is, connected to the 5GC via theinterface 120 and the interface 116, the SDAP 310 may be present as ahigher layer of the PDCP 206, which is a PDCP of the E-UTRA. The detailsare under discussion by the 3GPP.

Note that data processed in the MAC 302, the RLC 304, the PDCP 306, andthe SDAP 310 may be referred to as a MAC Protocol Data Unit (PDU), anRLC PDU, a PDCP PDU, and an SDAP PDU, respectively. In addition, thedata transferred from the higher layer to the MAC 202, the RLC 204, andthe PDCP 206 may be referred to as a MAC Service Data Unit (SDU), an RLCSDU, a PDCP SDU, and an SDAP SDU, respectively.

FIG. 3(B) is a protocol stack diagram of the CP used in a case that theUE 122 communicates with the gNB 108.

In addition to the PHY 300, the MAC 302, the RLC 304, and the PDCP 306,a Radio Resource Control (RRC) layer 308 is present in the protocolstack of the CP. The RRC 308 may configure and reconfigure Radio Bearers(RBs) to control the logical channels, the transport channels, and thephysical channels. The RBs may be classified into a Signaling RadioBearer (SRB) and a Data Radio Bearer (DRB), and the SRB may be used as apath for transmitting an RRC message which is control information. TheDRB may be used as a path for transmitting the user data. Each RB may beconfigured between the RRCs 208 of the gNB 108 and the UE 122 (NPL 10).

The functional classification of the MAC 302, the RLC 304, the PDCP 306,the SDAP 310, and the RRC 208 described above is an example, and some orall of the respective functions need not be implemented. Some or all ofthe functions of each layer may be included in another layer.

In the embodiments of the present invention, the MAC 202, the RLC 204,the PDCP 206, and the RRC 208 may be referred to as MAC for E-UTRA, RLCfor E-UTRA, RLC for E-UTRA, and RRC for E-UTRA, respectively todistinguish protocols of the E-UTRA and the NR hereinbelow. The MAC 302,the RLC 304, the PDCP 306, and the RRC 308 may also be referred to asMAC for NR, RLC for NR, RLC for NR, and RRC for NR, respectively.

As also illustrated in FIG. 1, the eNB 102, the gNB 108, the EPC 104,and the 5GC 110 may be connected to one another via the interface 112,the interface 116, the interface 118, the interface 120, and theinterface 114. Thus, the RRC 208 in FIG. 2 may be replaced with the RRC308 in FIG. 3 to support various communication systems. The PDCP 206 inFIG. 2 may also be replaced with the PDCP 306 in FIG. 3. The RRC 308 inFIG. 3 may include the function of the RRC 208 in FIG. 2. The PDCP 306in FIG. 3 may be the PDCP 206 in FIG. 2.

FIG. 4 is a drawing illustrating an example of a flow for an RRCconnection reconfiguration procedure according to each embodiment of thepresent invention.

The RRC connection reconfiguration procedure is a procedure used toperform handover, measurement, and the like, in addition toestablishment, change, and release of a RB, change and release of asecondary cell, and the like in the E-UTRA, which are described in NPL4. Meanwhile, the RRC connection reconfiguration procedure may be usedto perform establishment, change, and release of the RB, addition,change, and release of the secondary cell, handover and measurement, andthe like, which may be described in NPL 10. According to each embodimentof the present invention, the procedure used to perform establishment,change, and release of the RB, addition, change, and release of the cellgroup, handover and measurement, and the like is referred to as the RRCconnection reconfiguration procedure, or may have another designation.The RRC connection reconfiguration procedure according to eachembodiment of the present invention may be an RRC connectionreconfiguration procedure including establishing, changing, andreleasing the RB in the NR; adding, changing, and releasing the cellgroup; the handover and measurement; and the like.

As illustrated in FIG. 4, in a case that the RRC connectionreconfiguration is necessary, either the eNB 102 or the gNB 108 or boththe eNB 102 and the gNB 108 transmit an RRC connection reconfigurationrequest message (RRCConnectionReconfiguration message) to the UE 122(S400). The UE 122 that has received the RRC connection reconfigurationrequest message performs configuration in accordance with information(Information Element (IE)) or the like included in the RRC connectionreconfiguration request message, and may transmit an RRC ConnectionReconfiguration Complete message (RRCConnectionReconfigurationCompletemessage) to either the eNB 102 or the gNB 108 or both the eNB and thegNB, which are transmission sources of the RRC connectionreconfiguration request message to notify that the configuration iscompleted (S402). Note that the RRCConnectionReconfiguration message andthe RRCConnectionReconfigurationComplete message may have differentmessage designations. The UE 122 may transmit the RRC connectionreconfiguration complete message to both the eNB 102 and the gNB 108regardless of whether the base station apparatus that has transmittedthe RRC connection reconfiguration request is the eNB 102 or the gNB108. The UE 122 may transmit a complete message to both the eNB 102 andthe gNB 108 in response to a request message (RRCConnectionSetup,RRCConnectionReestablishment, or the like) transmitted from either theeNB 102 or the gNB 108 or both the eNB 102 and the gNB 108, not only inthe RRC connection reconfiguration procedure, but also in all or some ofother measures related to RRC (RRC connection establishment measures,RRC connection re-establishment measures, or the like), regardless ofwhether the base station apparatus that has transmitted the requestmessage is the eNB 102 or the gNB 108.

FIG. 5 is a block diagram illustrating a configuration of the terminalapparatus (UE) according to each embodiment of the present invention.Note that, FIG. 5 illustrates only main components closely related tothe present invention in order to avoid complicated description.

The UE 122 illustrated in FIG. 5 includes a receiver 500 that receivesan RRC connection reconfiguration request message from either the eNB102 or the gNB 108 or both the eNB and the gNB, and a configuration unit502 that configures a DRB in accordance with a DRB configuration in acase that DRB configuration information (DRB configuration) is includedin the RRC connection reconfiguration request message. The UE 122 mayinclude functions other than those of the receiver 500 and theconfiguration unit 502.

Embodiment 1

Embodiment 1 of the present invention will be described with referenceto FIG. 1 to FIG. 9.

FIG. 6 is a diagram illustrating an example of DRB configurationreception and configuration according to the embodiment of the presentinvention. Either the eNB 102 or the gNB 108 or both the eNB 102 and thegNB 108 determine the DRB configuration to be requested to the UE 122(S600). Either the eNB 102 or the gNB 108 or both the eNB 102 and thegNB 108 may determine the DRB configuration based on information fromthe core network (either the EPC 104 or the 5GC 110, or both the EPC 104and the 5GC 110), capability of the UE 122, or the information from thecore network and the capability of the UE 122. Note that the informationfrom the core network may be determined based on a condition of anapplication service, such as a voice call, requested by the UE 122.Next, either the eNB 102 or the gNB 108 or both the eNB 102 and the gNB108 generate an RRC Connection Reconfiguration request(RRCConnectionReconfiguration) message including the DRB configurationand transmit the message to the UE 122 (S602). The receiver 500 of theUE 122 receives the RRC connection reconfiguration request messageincluding the DRB configuration and transfers the DRB configuration tothe configuration unit 502.

FIGS. 7 and 8 each are one example of Abstract Syntax Notation One(ASN.1) for the DRB configuration. The specifications related to the RRC(NPL 4 and NPL 10) in the 3GPP describe messages, information(Information Element (IE)) related to the RRC, and the like by usingASN.1. Note that FIGS. 7 and 8 each are a part of one diagram. In otherwords, FIG. 7 is the first page of a diagram illustrating an example ofASN.1 for the DRB configuration, and FIG. 8 is the second page of thediagram illustrating an example of the ASN.1 related to the DRBconfiguration. In the examples of ASN.1 of FIGS. 7 and 8, <omitted> and<partly omitted> are not part of the description of ASN.1, but indicatethat other pieces of information are omitted. Note that information maybe omitted in a part where neither <omitted> or <partly omitted> isindicated.

In FIG. 8 among FIGS. 7 and 8, DRB-ToAddMod included in theRRCConnectionReconfiguration message is an IE of the DRB configuration.As illustrated in FIG. 8 among FIGS. 7 and 8, DRB-ToAddMod may includeDRB-Identity, which is an IE of a DRB identity, and PDCP-Config, whichis PDCP entity configuration information corresponding to the DRBidentity. As illustrated in FIG. 8 among FIGS. 7 and 8, PDCP-Config,which is the PDCP entity configuration information, may select (CHOICE)and include PDCP-EUTRA-Config, which is PDCP entity configurationinformation for E-UTRA, or PDCP-NR-Config, which is PDCP entityconfiguration information for NR. As illustrated in FIG. 8 among FIGS. 7and 8, PDCP-EUTRA-Config and PDCP-NR-Config may include pdcp-SN-Sizeinformation indicating a length of a Sequence Number (SN) of the PDCP,and the pdcp-SN-Size may be an integer including 7.

FIGS. 16, 17, and 18 illustrate another example of Abstract SyntaxNotation One (ASN.1) for the DRB configuration. Note that FIGS. 16, 17,and 18 each are a part of one diagram. In other words, FIG. 16 is thefirst page of a diagram illustrating the other example of ASN.1 for theDRB configuration, FIG. 17 is the second page of the diagramillustrating the other example of ASN.1 for the DRB configuration, andFIG. 18 is the third page of the diagram illustrating the other exampleof ASN.1 for the DRB configuration. In the example of ASN.1 in FIGS. 16,17, and 18, <omitted> and <partly omitted> are not part of thedescription of the ASN.1, but indicate that other pieces of informationare omitted. Note that information may be omitted in a part whereneither <omitted> or <partly omitted> is indicated.

In FIG. 16 among FIGS. 16, 17, and 18, the RRCConnectionReconfigurationmessage may select (CHOICE) and includeRRCConnectionReconfiguration-EUTRA-IE, which is an IE of an RRCconnection reconfiguration request for E-UTRA, orRRCConnectionReconfiguration-NR-IE, which is an IE of an RRC connectionreconfiguration request for NR.

As illustrated in FIGS. 16 and 17 among FIGS. 16, 17, and 18, in a casethat the IE of the RRC connection reconfiguration request for E-UTRA isselected, DRB-ToAddMod-EUTRA, which is an IE of the DRB configurationfor E-UTRA, may be included. As illustrated in FIG. 17 among FIGS. 16,17, and 18, DRB-ToAddMod-EUTRA may include DRB-Identity, which is an IEof the DRB identity, and PDCP-Config-EUTRA, which is PDCP entityconfiguration information for E-UTRA corresponding to the DRB identity.As illustrated in FIGS. 17 and 18 among FIGS. 16, 17, and 18,PDCP-Config-EUTRA, which is PDCP entity configuration information forE-UTRA, may further select (CHOICE) and include PDCP-EUTRA-Config, whichis the PDCP entity configuration information for E-UTRA, orPDCP-NR-Config, which is the PDCP entity configuration information forNR, as a PDCP entity configuration for E-UTRA. As illustrated in FIG. 18among FIGS. 16, 17, and 18, PDCP-EUTRA-Config and PDCP-NR-Config mayinclude the pdcp-SN-Size information indicating the length of theSequence Number (SN) of the PDCP, and the pdcp-SN-Size may be an integerincluding 7.

As illustrated in FIG. 16 and FIG. 17 among FIGS. 16, 17, and 18, in acase that the IE of the RRC connection reconfiguration request for NR isselected, DRB-ToAddMod-NR, which is an IE of the DRB configuration forNR, may be included. As illustrated in FIG. 17 among FIGS. 16, 17, and18, DRB-ToAddMod-NR may include the DRB-Identity, which is the IE of theDRB identity, and PDCP-Config-NR, which is the PDCP entity configurationinformation for NR corresponding to the DRB identity. As illustrated inFIGS. 17 and 18 among FIGS. 16, 17, and 18, PDCP-Config-NR, which is thePDCP entity configuration information for NR, may further select(CHOICE) and include PDCP-EUTRA-Config, which is the PDCP entityconfiguration information for E-UTRA, or PDCP-NR-Config, which is thePDCP entity configuration information for NR, as a PDCP entityconfiguration for NR. As illustrated in FIG. 18 among FIGS. 16, 17, and18, PDCP-EUTRA-Config and PDCP-NR-Config may include the pdcp-SN-Sizeinformation indicating the length of the Sequence Number (SN) of thePDCP, and the pdcp-SN-Size may be an integer including 7.

Note that the message designation, IE designation, parameterdesignation, and the like of ASN.1 in FIGS. 7 and 8, and FIGS. 16, 17,and 18 are examples and other designations may be possible. In FIGS. 7and 8, and FIGS. 16, 17, and 18, an RLC entity for E-UTRA and an RLCentity for NR may be described in a similar manner to the description ofa PDCP entity for E-UTRA and a PDCP entity for NR. Also, in FIGS. 7 and8, and FIGS. 16, 17, and 18, a MAC entity for E-UTRA (such asMACMainConfig (not illustrated) and logicalChannelConfig) and a MACentity for NR may be described in a similar manner to the description ofthe PDCP entity for E-UTRA and the PDCP entity for NR.

In S604 of FIG. 6, the DRB configuration that the receiver 500 of the UE122 transfers to the configuration unit 502 of the UE 122 includes atleast the DRB identity and either the PDCP entity configuration forE-UTRA or the PDCP entity configuration for NR as a PDCP entityconfiguration corresponding to the DRB identity. The configuration unit502 of the UE 122 establishes or reestablishes the PDCP entity inaccordance with the DRB identity and the PDCP entity configurationcorresponding to the DRB identity.

FIG. 9 is an example of determination of the PDCP configuration by theconfiguration unit of the terminal apparatus according to the embodimentof the present invention. The configuration unit 502 of the UE 122checks whether a value of the DRB identity is present in the currentconfiguration of the terminal apparatus (S900). In a case that the valueis absent, whether the PDCP entity for E-UTRA is included in the PDCPentity configuration corresponding to the DRB identity is checked(S902). In a case that the PDCP entity for E-UTRA is included, the PDCPentity for E-UTRA is established in accordance with the PDCP entityconfiguration information for E-UTRA (S904). On the other hand, in acase that the PDCP entity configuration corresponding to the DRBidentity does not include the PDCP entity for E-UTRA, whether the PDCPentity configuration corresponding to the DRB identity includes the PDCPentity for NR is further checked (S906). In a case that the PDCP entityfor NR is included, the PDCP entity for NR is established in accordancewith the PDCP entity configuration information for NR (S908). In a casethat the PDCP entity configuration corresponding to the DRB identitydoes not include the PDCP entity for NR, another configuration isperformed (S918).

On the other hand, in a case that the value of the DRB identity ispresent in the current configuration of the terminal apparatus, whetherthe PDCP entity configuration corresponding to the DRB identity includesthe PDCP entity for E-UTRA is checked (S910). In a case that the PDCPentity for E-UTRA is included, the PDCP entity for E-UTRA isreestablished in accordance with the PDCP entity configurationinformation for E-UTRA (S912). On the other hand, in a case that thePDCP entity configuration corresponding to the DRB identity does notinclude the PDCP entity for E-UTRA, whether the PDCP entityconfiguration corresponding to the DRB identity includes the PDCP entityfor NR is further checked (S914). In a case that the PDCP entity for NRis included, the PDCP entity for NR is reestablished in accordance withthe PDCP entity configuration information for NR (S916). In a case thatthe PDCP entity configuration corresponding to the DRB identity does notinclude the PDCP entity for NR, another configuration is performed(S918). The reestablishment processing may switch the entity between thePDCP entity for E-UTRA and the PDCP entity for NR. For example, in acase that the PDCP entity configuration corresponding to a certain DRBidentity (denoted as a DRB identity 1) present in the currentconfiguration of the UE 122 is the PDCP entity for E-UTRA and in a casethat the DRB configuration included in the received RRC connectionreconfiguration message includes the above-described DRB identity 1 andthe PDCP entity configuration corresponding to the DRB identity 1 is thePDCP entity configuration for NR, the PDCP entity corresponding to theDRB identity 1 is reconfigured as the PDCP entity for NR. Similarly, ina case that the PDCP entity configuration corresponding to a certain DRBidentity (denoted as a DRB identity 2) present in the currentconfiguration of the UE 122 is the PDCP entity for NR, and in a casethat the DRB configuration included in the received RRC connectionreconfiguration message includes the above-described DRB identity 2 andthe PDCP entity configuration corresponding to the DRB identity 2 is thePDCP entity configuration for E-UTRA, the PDCP entity corresponding tothe DRB identity 2 is reconfigured as the PDCP entity for E-UTRA. Inthis manner, the PDCP entity configuration for E-UTRA and the PDCPentity configuration for NR may be switched by the RRC connectionreconfiguration message.

In FIG. 6, after completing the configuration in the configuration unit502 of the UE 122, the UE 122 transmits the RRC ConnectionReconfiguration Complete (RRCConnectionReconfigurationComplete) messageto either the eNB 102 or the gNB 108 or both the eNB 102 and the gNB 108(S606).

Note that the DRB configuration according to the present embodiment maybe included in an RRC Connection Establishment procedure and an RRCConnection Re-establishment procedure, in addition to the RRC connectionreconfiguration procedure. The reestablishment of the PDCP entity in thepresent embodiment may include, for example, zero reset of a Hyper FrameNumber (HFN), a change to an initial (Initialization and Refresh (IR))mode of header compression, a change to a designated cryptographicalgorithm and cryptographic key, and the like, which are described inNPL 5.

Note that the zero reset of the Hyper Frame Number (HFN), the change tothe initial (Initialization and Refresh (IR)) mode of headercompression, and the change to the designated cryptographic algorithmand cryptographic key, which are described in Non Patent Literature, arefor E-UTRA, but may be applied for NR.

Thus, in the present embodiment, based on a condition of an applicationservice, such as a voice call, requested by the terminal apparatus (UE)and the like, the base station apparatus of E-UTRA (eNB) or the basestation apparatus of NR (gNB), or the eNB and gNB select whether thePDCP entity to be used in communication with the UE is for E-UTRA or NR,and notify the UE of the result of the selection using the RRCconnection reconfiguration message. Thus, the PDCP entity suitable forthe application service used by the UE can be established, andcommunication can be efficiently performed with reduced complexity ofprotocol processing.

Embodiment 2

In Embodiment 2 of the present invention, a DRB configuration in a caseof E-UTRAN supports Multi-RAT Dual Connectivity (MR-DC) via E-UTRA-NRDual Connectivity (EN-DC) will be described below. In the EN-DC,especially an EPC serves as a core network and the base stationapparatus on the E-UTRA side serves as a master base station apparatusdescribed later in Multi-RAT Dual Connectivity (MR-DC). The MR-DC is amechanism that has been studied as one of technologies for NR. In theMR-DC, cells of Radio Access Technologies (RATs) of both E-UTRA and NRare cell-grouped for each RAT and allocated to a UE for communicationbetween the UE and one or more base station apparatuses.

The second embodiment will be described with reference to FIG. 1 andFIGS. 5 to 12.

FIG. 10 is a diagram illustrating an example of a relationship betweenradio protocol architecture and RBs in the EN-DC on the base stationapparatus side according to the embodiment of the present invention.

The EN-DC may be a technology for performing data communication by usingradio resources of two cell groups respectively configured by two basestation apparatuses with EPC as a core network. The two base stationapparatuses, that is, a base station apparatus of E-UTRA as a masterbase station (Master eNB (MeNB)) and a base station apparatus of NR as asecondary base station (Secondary gNB (SgNB)) respectively configuresthe two cell groups, that is a Master Cell Group (MCG) configured by theMeNB and a Secondary Cell Group (SCG) configured by the SgNB. In theMR-DC, the master base station may be a base station having main RRCfunctions related to the MR-DC, for example, establishment, change, andrelease of the RB, addition, change, and release of an additional cellsuch as a secondary cell, handover, and the like, and the secondary basestation may be a base station having some RRC functions, for example,change and release of the SCG, and the like.

As illustrated in FIG. 10, in the EN-DC, some pieces of data to betransmitted and/or received are transmitted and/or received on the SgNBside, and the remainder is transmitted and/or received on the MeNB side.A data transmission and/or reception method in the EN-DC may include amethod in which a node in the EPC serves as an anchor point as a pointof bifurcation and confluence of data and each of the MeNB and the SgNBestablishes a bearer as a logical path with the EPC to perform datatransmission and/or reception, that is, data is transmitted and/orreceived using an MCG bearer on the MeNB side and an SCG bearer on theSgNB side, and a method in which the MeNB or the SeNB serves as theanchor point, and data transmission and/or reception is performed usinga split bearer obtained by splitting a Radio Bearer (RB), which is abearer on the radio side, for the MeNB and the SeNB. As for the splitbearer, there may be a method for establishing the split bearer at thetime of establishing the radio bearer and a method for establishing theMCG bearer or the SCG bearer and then changes the MCG bearer or the SCGbearer to the split bearer by adding the radio bearer on the SCG side orthe MCG side. The establishment and change of the MCG bearer, the SCGbearer, and the split bearer may be performed by a Radio ResourceControl (RRC) Connection Reconfiguration procedure transmitted betweenthe MeNB and the UE. In the present embodiment, the cell group of thebase station apparatus serving as the anchor point of the split beareris referred to as an anchor cell Group and the cell group of the basestation apparatus that does not serve as the anchor point of the splitbearer is referred to as an additional cell group. The anchor cell groupmay be the MCG and the additional cell group may be the SCG, or theanchor cell group may be the SCG and the additional cell group may bethe MCG. The split bearer in the case that the anchor cell group is theMCG may be referred to as an MCG split bearer, or the split bearer inthe case that the anchor cell group is the SCG may be referred to as anSCG split bearer.

In the EN-DC, with respect to downlink data in a case of datatransmission and/or reception using the split bearer, part of thedownlink data transferred from the EPC may be distributed by the basestation apparatus of the anchor cell group to the base station apparatusof the additional cell group, and transmitted by the base stationapparatus of the additional cell group to the UE, and the remaining datamay be transmitted from the base station apparatus of the master cellgroup to the UE. With respect to uplink data, part of the uplink datamay be transmitted by the UE to the base station apparatus of theadditional cell group and distributed by the base station apparatus ofthe additional cell group to the base station apparatus of the mastercell group, and the remaining data may be transmitted by the UE to thebase station apparatus of the master cell group.

As illustrated in FIG. 10, in a case that the split bearer is used, thePDCP PDU may be transmitted and/or received between the base stationapparatus of the master cell group and the base station apparatus of theadditional cell group.

FIG. 11 is a diagram illustrating an example of the DRB configurationreception and configuration in a case that the MCG bearer or the SCGbearer is established as a bearer of an anchor cell group according tothe embodiment of the present invention. Note that even in a case that abearer is established as the anchor cell group, the bearer need not bechanged to the split bearer later. The eNB 102 determines the DRBconfiguration to be requested to the UE 122 (S1100). The eNB 102 maydetermine the DRB configuration based on either information from thecore network (EPC 104) or capability of the UE 122, or the informationfrom the core network and the capability of the UE 122. Note that theinformation from the core network may be determined based on a conditionof an application service, such as a voice call, requested by the UE122. Next, the eNB 102 generates the RRC connection reconfigurationrequest (RRCConnectionReconfiguration) message including the DRBconfiguration and transmits the message to the UE 122 (S1102). Thereceiver 500 of the UE 122 receives the RRC connection reconfigurationrequest message including the DRB configuration and transfers the DRBconfiguration to the configuration unit 502.

FIGS. 7 and 8 are one example of Abstract Syntax Notation One (ASN.1)for the DRB configuration described in Embodiment 1.

In other words, in FIG. 8 among FIGS. 7 and 8, DRB-ToAddMod included inthe RRCConnectionReconfiguration message is the IE of the DRBconfiguration. As illustrated in FIG. 8 among FIGS. 7 and 8,DRB-ToAddMod may include a DRB-Identity, which is an IE of a DRBidentity, and PDCP-Config, which is PDCP entity configurationinformation corresponding to the DRB identity. As illustrated in FIG. 8among FIGS. 7 and 8, PDCP-Config, which is the PDCP entity configurationinformation, may select (CHOICE) and include PDCP-EUTRA-Config, which isthe PDCP entity configuration information for E-UTRA, or PDCP-NR-Config,which is the PDCP entity configuration information for NR. Asillustrated in FIG. 8 among FIGS. 7 and 8, PDCP-EUTRA-Config andPDCP-NR-Config may include pdcp-SN-Size information indicating thelength of the Sequence Number (SN) of the PDCP, and the pdcp-SN-Size maybe an integer including 7.

FIGS. 16, 17, and 18 illustrate another example of Abstract SyntaxNotation One (ASN.1) for the DRB configuration described in Embodiment1.

That is, in FIG. 16 among FIGS. 16, 17, and 18, theRRCConnectionReconfiguration message may select (CHOICE) and include theRRCConnectionReconfiguration-EUTRA-IE, which is the IE of the RRCconnection reconfiguration request for E-UTRA, or theRRCConnectionReconfiguration-NR-IE, which is the IE of the RRCconnection reconfiguration request for NR.

As illustrated in FIGS. 16 and 17 among FIGS. 16, 17, and 18, in a casethat the IE of the RRC connection reconfiguration request for E-UTRA isselected, DRB-ToAddMod-EUTRA, which is the IE of the DRB configurationfor E-UTRA, may be included. As illustrated in FIG. 17 among FIGS. 16,17, and 18, DRB-ToAddMod-EUTRA may include the DRB-Identity, which isthe IE of the DRB identity, and PDCP-Config-EUTRA, which is the PDCPentity configuration information for E-UTRA corresponding to the DRBidentity. As illustrated in FIGS. 17 and 18 among FIGS. 16, 17, and 18,PDCP-Config-EUTRA, which is the PDCP entity configuration informationfor E-UTRA, may further select (CHOICE) and include PDCP-EUTRA-Config,which is the PDCP entity configuration information for E-UTRA, orPDCP-NR-Config, which is the PDCP entity configuration information forNR, as the PDCP entity configuration for E-UTRA. As illustrated in FIG.18 among FIGS. 16, 17, and 18, PDCP-EUTRA-Config and PDCP-NR-Config mayinclude the pdcp-SN-Size information indicating the length of theSequence Number (SN) of the PDCP, and the pdcp-SN-Size may be an integerincluding 7.

As illustrated in FIGS. 16 and 17 among FIGS. 16, 17, and 18, in a casethat the IE of the RRC connection reconfiguration request for NR isselected, DRB-ToAddMod-NR, which is the IE of the DRB configuration forNR, may be included. As illustrated in FIG. 17 among FIGS. 16, 17, and18, DRB-ToAddMod-NR may include the DRB-Identity, which is the IE of theDRB identity, and PDCP-Config-NR, which is the PDCP entity configurationinformation for NR corresponding to the DRB identity. As illustrated inFIGS. 17 and 18 among FIGS. 16, 17, and 18, PDCP-Config-NR, which is thePDCP entity configuration information for NR, may further select(CHOICE) and include PDCP-EUTRA-Config, which is the PDCP entityconfiguration information for E-UTRA, or PDCP-NR-Config, which is thePDCP entity configuration information for NR, as the PDCP entityconfiguration for NR. As illustrated in FIG. 18 among FIGS. 16, 17, and18, PDCP-EUTRA-Config and PDCP-NR-Config may include the pdcp-SN-Sizeinformation indicating the length of the Sequence Number (SN) of thePDCP, and the pdcp-SN-Size may be an integer including 7.

Note that, as described in Embodiment 1, the message designation, IEdesignation, parameter designation, and the like of ASN.1 in FIGS. 7 and8, and FIGS. 16, 17, and 18 are examples and other designations may bepossible. In FIGS. 7 and 8, and FIGS. 16, 17, and 18, an RLC entity forE-UTRA and an RLC entity for NR may be described in a similar manner tothe description of a PDCP entity for E-UTRA and a PDCP entity for NR.Also, in FIGS. 7 and 8, and FIGS. 16, 17, and 18, the MAC entity forE-UTRA (such as MACMainConfig (not illustrated) andlogicalChannelConfig) and the MAC entity for NR may be described in asimilar manner to the description of the PDCP entity for E-UTRA and thePDCP entity for NR.

In S1104 of FIG. 11, the DRB configuration that the receiver 500 of theUE 122 transfers to the configuration unit 502 of the UE 122 includes atleast the DRB identity and either the PDCP entity configuration forE-UTRA or the PDCP entity configuration for NR as the PDCP entityconfiguration corresponding to the DRB identity. The configuration unit502 of the UE 122 establishes or reestablishes the PDCP entity inaccordance with the DRB identity and the PDCP entity configurationcorresponding to the DRB identity.

As described in Embodiment 1, FIG. 9 is an example of determination ofthe PDCP configuration by the configuration unit of the terminalapparatus. In other words, the configuration unit 502 of the UE 122checks whether the value of the DRB identity is present in the currentconfiguration of the terminal apparatus (S900). In a case that the valueis absent, whether the PDCP entity for E-UTRA is included in the PDCPentity configuration corresponding to the DRB identity is checked(S902). In a case that the PDCP entity for E-UTRA is included, the PDCPentity for E-UTRA is established in accordance with the PDCP entityconfiguration information for E-UTRA (S904). On the other hand, in acase that the PDCP entity configuration corresponding to the DRBidentity does not include the PDCP entity for E-UTRA, whether the PDCPentity configuration corresponding to the DRB identity includes the PDCPentity for NR is further checked (S906). In a case that the PDCP entityfor NR is included, the PDCP entity for NR is established in accordancewith the PDCP entity configuration information for NR (S908). In a casethat the PDCP entity configuration corresponding to the DRB identitydoes not include the PDCP entity for NR, another configuration isperformed (S918).

On the other hand, in a case that the value of the DRB identity ispresent in the current configuration of the terminal apparatus, whetherthe PDCP entity configuration corresponding to the DRB identity includesthe PDCP entity for E-UTRA is checked (S910). In a case that the PDCPentity for E-UTRA is included, the PDCP entity for E-UTRA isreestablished in accordance with the PDCP entity configurationinformation for E-UTRA (S912). On the other hand, in a case that thePDCP entity configuration corresponding to the DRB identity does notinclude the PDCP entity for E-UTRA, whether the PDCP entityconfiguration corresponding to the DRB identity includes the PDCP entityfor NR is further checked (S914). In a case that the PDCP entity for NRis included, the PDCP entity for NR is reestablished in accordance withthe PDCP entity configuration information for NR (S916). In a case thatthe PDCP entity configuration corresponding to the DRB identity does notinclude the PDCP entity for NR, another configuration is performed(S918). The reestablishment processing may switch the entity between thePDCP entity for E-UTRA and the PDCP entity for NR. For example, in acase that the PDCP entity configuration corresponding to a certain DRBidentity (denoted as a DRB identity 1) present in the currentconfiguration of the UE 122 is the PDCP entity for E-UTRA and in a casethat the DRB configuration included in the received RRC connectionreconfiguration message includes the above-described DRB identity 1 andthe PDCP entity configuration corresponding to the DRB identity 1 is thePDCP entity configuration for NR, the PDCP entity corresponding to theDRB identity 1 is reconfigured as the PDCP entity for NR. Similarly, ina case that the PDCP entity configuration corresponding to a certain DRBidentity (denoted as a DRB identity 2) present in the currentconfiguration of the UE 122 is the PDCP entity for NR, and in a casethat the DRB configuration included in the received RRC connectionreconfiguration message includes the above-described DRB identity 2 andthe PDCP entity configuration corresponding to the DRB identity 2 is thePDCP entity configuration for E-UTRA, the PDCP entity corresponding tothe DRB identity 2 is reconfigured as the PDCP entity for E-UTRA. Inthis manner, the PDCP entity configuration for E-UTRA and the PDCPentity configuration for NR may be switched by the RRC connectionreconfiguration message.

In FIG. 11, after completing the configuration in the configuration unit502 of the UE 122, the UE 122 transmits the RRC ConnectionReconfiguration Complete (RRCConnectionReconfigurationComplete) messageto the eNB 102 (S1106).

Note that the DRB configuration according to the present embodiment maybe included in an RRC Connection Establishment procedure and an RRCConnection Reestablishment procedure, in addition to the RRC connectionreconfiguration procedure. The reestablishment of the PDCP entityaccording to the present embodiment may include, for example, zero resetof a Hyper Frame Number (HFN), a change to an initial (Initializationand Refresh (IR)) mode of header compression, a change to a designatedcryptographic algorithm and cryptographic key, and the like, which aredescribed in NPL 5.

Note that the zero reset of the Hyper Frame Number (HFN), the change tothe initial (Initialization and Refresh (IR)) mode of headercompression, and the change to the designated cryptographic algorithmand cryptographic key, which are described in Non Patent Literature, arefor E-UTRA, but may be applied for NR.

Next, a change from the MCG bearer or the SCG bearer to the split bearerwill be described.

FIG. 12 is an example of Abstract Syntax Notation One (ASN.1) for theDRB configuration of the additional cell group in a case that the MCGbearer or the SCG bearer is changed to the split bearer. In the exampleof ASN.1 in FIG. 12, <omitted> and <partly omitted> are not part of thedescription of ASN.1, but indicate that other pieces of information areomitted. Note that information may be omitted in a part where <omitted>or <partly omitted> is not described. The example of ASN.1 illustratedin FIG. 12 may be a part of the examples of ASN.1 illustrated in FIGS. 7and 8, or FIGS. 16, 17, and 18. The IE of DRB-ToAddModADDCG-NR IEillustrated in FIG. 12 is related to the DRB configuration of anadditional cell group and may have another designation. The IE ofDRB-ToAddModADDCG-NR IE illustrated in FIG. 12 may be a part of a higherIE related to additional cell group configuration.

In FIG. 11, the eNB 102 determines the DRB configuration of the anchorcell group to be requested to the UE 122 and the DRB configuration ofthe additional cell group (S1100). However, the DRB configuration of theanchor cell group need not be changed. In a case that the DRBconfiguration of the anchor cell group is changed, the DRB configurationof the anchor cell group may include the DRB identity and entityconfiguration information, such as the PDCP entity configuration to bechanged corresponding to the DRB identity. Additionally, in a case thatthe DRB configuration of the anchor cell group is not changed, the DRBconfiguration of the anchor cell group may include only the DRBidentity. The eNB 102 may determine whether to change the DRBconfiguration of the anchor cell group based on either the informationfrom the core network (EPC 104) or the capability of the UE 122, or theinformation from the core network and the capability of the UE 122. Notethat the information from the core network may be determined based on acondition of an application service, such as a voice call, requested bythe UE 122. Next, the eNB 102 generates the RRC connectionreconfiguration request (RRCConnectionReconfiguration) message includingthe DRB configuration of the anchor cell and the DRB configuration ofthe additional cell and transmits the message to the UE 122 (S1102). Thereceiver 500 of the UE 122 receives the RRC connection reconfigurationrequest message including the DRB configuration of the anchor cell andthe DRB configuration of the additional cell and transfers the DRBconfiguration of the anchor cell and the DRB configuration of theadditional cell to the configuration unit 502.

In a case that a value of the DRB identity included in the DRBconfiguration of the anchor cell group is present in the currentconfiguration of the UE 122 and in a case that the DRB identity includedin the DRB configuration of the anchor cell group is the DRB identityincluded in the DRB configuration of the additional cell group, that is,in a case that the value of the DRB identity of the anchor cell groupand the value of the DRB identity of the additional cell group are thesame, and in a case that a DRB type of the additional cell group (suchas drb-Type-NR in FIG. 12) is split, the configuration unit 502 of theUE 122 determines to change the MCG bearer or the SCG bearer that isalready present to the split bearer. Note that the determination methodfor changing the MCG bearer or the SCG bearer that is already present tothe split bearer is not limited to the above, and another method may beapplied.

The configuration unit 502 of the UE 122 may establish the DRB of theadditional cell group in accordance with the DRB configuration of theadditional cell group, and may reestablish the PDCP entity in accordancewith the PDCP entity configuration in a case that the PDCP entityconfiguration corresponding to the DRB identity is present in the DRBconfiguration of the anchor cell group. The reestablishment processingmay switch the entity between the PDCP entity for E-UTRA and the PDCPentity for NR. For example, in a case that the PDCP entity configurationcorresponding to a certain DRB identity (denoted as a DRB identity 1)present in the current configuration of the UE 122 is the PDCP entityfor E-UTRA and in a case that the DRB configuration included in thereceived RRC connection reconfiguration message includes theabove-described DRB identity 1 and the PDCP entity configurationcorresponding to the DRB identity 1 is the PDCP entity configuration forNR, the PDCP entity corresponding to the DRB identity 1 is reconfiguredas the PDCP entity for NR. Similarly, in a case that the PDCP entityconfiguration corresponding to a certain DRB identity (denoted as a DRBidentity 2) present in the current configuration of the UE 122 is thePDCP entity for NR, and in a case that the DRB configuration included inthe received RRC connection reconfiguration message includes theabove-described DRB identity 2 and the PDCP entity configurationcorresponding to the DRB identity 2 is the PDCP entity configuration forE-UTRA, the PDCP entity corresponding to the DRB identity 2 isreconfigured as the PDCP entity for E-UTRA. In this manner, the PDCPentity configuration for E-UTRA and the PDCP entity configuration for NRmay be switched by the RRC connection reconfiguration message.

Thus, according to the present embodiment, in the case of the EN-DC aswell, based on a condition of an application service, such as a voicecall, requested by the terminal apparatus (UE) and the like, the anchorcell group selects whether the PDCP entity used in communication withthe UE is for E-UTRA or NR, and notifies the UE of the result of theselection using the RRC connection reconfiguration message. Thus, withthe EN-DC as well, the PDCP entity suitable for the application serviceused by the UE can be established, and communication can be efficientlyperformed with reduced complexity of protocol processing.

Embodiment 3

In Embodiment 3 of the present invention, a DRB configuration includingan SDAP entity configuration in a case that the core network is the 5GC110 will be described. In Embodiment 3, the UE 122 may communicate withthe 5GC 110 via the gNB, may communicate with the 5GC via the eNB, ormay communicate with the 5GC using the MR-DC in which both of the gNBand the eNB are used.

The Embodiment 3 will be described with reference to FIGS. 1, 5, 7, and8, and FIGS. 13 to 15, FIGS. 16, 17, and 18.

FIG. 13 is a drawing illustrating an example of DRB configurationreception and configuration according to the embodiment of the presentinvention. Either the eNB 102 or the gNB 108 or both the eNB 102 and thegNB 108 determine the DRB configuration including the SDAP entityconfiguration requested to the UE 122 (S1300). Either the eNB 102 or thegNB 108 or both the eNB 102 and the gNB 108 may determine the DRBconfiguration based on information from the core network (either the EPC104 or the 5GC 110, or both the EPC 104 and the 5GC 110) or capabilityof the UE 122, or the information from the core network and thecapability of the UE 122. Note that the information from the corenetwork may be determined based on a condition of an applicationservice, such as a voice call, requested by the UE 122. The DRBconfiguration may include information on the SDAP, such as an SDAPheader length. The information on the SDAP may be included in the SDAPentity configuration, or may be included in another entityconfiguration, such as the PDCP entity configuration. Next, either theeNB 102 or the gNB 108 or both the eNB 102 and the gNB 108 generate anRRC connection reconfiguration request (RRCConnectionReconfiguration)message including the DRB configuration and transmit the message to theUE 122 (S1302). The receiver 500 of the UE 122 receives the RRCconnection reconfiguration request message including the DRBconfiguration and transfers the DRB configuration to the configurationunit 502.

FIGS. 14 and 15 are examples of Abstract Syntax Notation One (ASN.1) forthe DRB configuration including the SDAP information according to theembodiment of the present invention. In the examples of ASN.1 in FIGS.14 and 15, <omitted> and <partly omitted> are not part of thedescription of ASN.1, but indicate that other pieces of information areomitted. Note that information may be omitted in a part where <omitted>or <partly omitted> is not indicated.

FIG. 14 is an example in which the SDCP entity configuration includesSDCP header length information, and FIG. 15 is an example in whichanother PDCP entity configuration includes a SDCP header length. TheSDCP header length information may be information included in either theSDCP entity configuration or the PDCP entity configuration, or may beinformation included in both the SDCP entity configuration and the PDCPentity configuration. The SDAP header length may be a length of amultiple of eight including zero (0). For example, in the examples ofFIGS. 14 and 15, “len0bits,” “len8bits,” “len16bits,” and “len24bits”may be 0 bits, 8 bits, 12 bits, and 24 bits, respectively.Alternatively, it may be indicated in units of byte such as “len0bytes,”“len1bytes,” “len2 bytes,” and “len3 bytes,” or in units of octet. Notethat the length of the SDAP header being zero may mean that no SDAPheader is present. Additionally, an indication and a designation of theSDAP header length are not limited to thereto, and another notation anddesignation may be possible. A message designation, IE designation,parameter designation, and the like of ASN.1 in FIGS. 14 and 15 areexamples and other designations may be possible. The example of ASN.1illustrated in FIGS. 14 and 15 may be a part of the example of ASN.1illustrated in FIGS. 7 and 8, or FIGS. 16, 17, and 18.

The configuration unit 502 of the UE 122 will be described using theexample of FIG. 14, that is, an example in a case that the SDAP entityconfiguration includes the SDAP header length. In S1304 of FIG. 13, theDRB configuration that the receiver 500 of the UE 122 transfers to theconfiguration unit 502 of the UE 122 includes at least the DRB identityand the SDAP entity configuration corresponding to the DRB identity, andthe SDAP entity configuration includes the SDAP header length. Theconfiguration unit 502 of the UE 122 establishes or reestablishes theSDAP entity in accordance with the DRB identity and the SDAP entityconfiguration corresponding to the DRB identity. In other words, in acase that a value of the DRB identity transferred from the receiver 500is not present in the current configuration of the terminal apparatus,the SDAP entity may be established. In a case that the value of the DRBidentity transferred from the receiver 500 is present in the currentconfiguration of the terminal apparatus, the SDAP entity may bereestablished. Note that, in a case of the length of the SDAP headerbeing zero, a process of establishing the SDAP entity but not admittingthe presence of the SDAP header may be performed, or a process of notestablishing the SDAP entity may be performed.

The configuration unit 502 of the UE 122 will be described using theexample of FIG. 15, that is, an example in a case that the PDCP entityconfiguration includes the SDAP header length. In S1304 of FIG. 13, theDRB configuration that the receiver 500 of the UE 122 transferred to theconfiguration unit 502 of the UE 122 includes at least the DRB identityand the PDCP entity configuration corresponding to the DRB identity, andthe PDCP entity configuration includes the SDAP header length. Theconfiguration unit 502 of the UE 122 establishes or reestablishes thePDCP entity in accordance with the DRB identity and the PDCP entityconfiguration corresponding to the DRB identity. In other words, in acase that the value of the DRB identity transferred from the receiver500 is not present in the current configuration of the terminalapparatus, the PDCP entity may be established. In a case that the valueof the DRB identity transferred from the receiver 500 is present in thecurrent configuration of the terminal apparatus, the PDCP entity may bereestablished. The established or reestablished PDCP entity may identifyan SDAP SDU, that is, a starting position of IP packets from the SDAPheader length information, and perform header compression processing.Note that even in a case that the SDAP header length is not included inthe PDCP entity configuration and included in the SDAP entityconfiguration, the PDCP entity may identify the SDAP SDU, that is, thestarting position of IP packets, from the SDAP header length informationincluded in the SDAP entity configuration and perform header compressionprocessing.

In FIG. 13, after completing the configuration in the configuration unit502 of the UE 122, the UE 122 transmits an RRC ConnectionReconfiguration Complete (RRCConnectionReconfigurationComplete) messageto either the eNB 102 or the gNB 108 or both the eNB 102 and the gNB 108(S1306).

Note that the DRB configuration according to the present embodiment maybe included in an RRC Connection Establishment procedure and an RRCConnection Reestablishment procedure, in addition to the RRC connectionreconfiguration procedure. The reestablishment of the PDCP entityaccording to the present embodiment may include, for example, zero resetof a Hyper Frame Number (HFN), a change to an initial (Initializationand Refresh (IR)) mode of header compression, a change to a designatedcryptographic algorithm and cryptographic key, and the like, which aredescribed in NPL 5.

Note that the zero reset of the Hyper Frame Number (HFN), the change tothe initial (Initialization and Refresh (IR)) mode of headercompression, and the change to the designated cryptographic algorithmand cryptographic key, which are described in Non Patent Literature, arefor E-UTRA, but may be applied for NR.

While the DRB configuration according to the present embodiment assumesa case that the core network is 5GC, the DRB configuration may also beapplied to a case that the core network is EPC.

Thus, in the present embodiment, based on a condition of an applicationservice, such as a voice call, requested by the terminal apparatus (UE)and the like, either the base station apparatus in the E-UTRA (eNB) orthe base station apparatus in the NR (gNB), or the eNB and gNB performthe SDAP entity configuration including the SDAP header length or thePDCP entity configuration including the SDAP header length to be used incommunication with the UE, and notify the UE of the configuration usingthe RRC connection reconfiguration message. Accordingly, the SDAP headerlength suitable for the application service used by the UE can be used,and header compression by the PDCP entity can be performed as needed,and communication can be efficiently performed with reduced complexityof protocol processing.

Note that while the notations regarding the RRC according to eachembodiment of the present invention, for example, a message such as anRRC connection reconfiguration request message, ASN.1, and the like areprovided on the assumption of the RRC for NR (for example, the RRCdescribed in NPL 9 or NPL 10), they may be for LTE expansion, and may betransmitted and/or received between the base station apparatus forE-UTRA and the terminal apparatus supporting the MR-DC.

In addition, the reestablishment of each entity, such as the PDCP entityaccording to each embodiment of the present invention, may be performedby the RRC connection reconfiguration procedure at the time of handover.In addition, at the time of the reestablishment of each entity, such asthe PDCP entity according to each embodiment of the present invention,security configuration may also be reconfigured.

A program operating on an apparatus according to the present inventionmay serve as a program that controls a Central Processing Unit (CPU) andthe like to cause a computer to operate in such a manner as to achievethe functions of the above-described embodiments according to thepresent invention. Programs or the information handled by the programsare temporarily read into a volatile memory, such as a Random AccessMemory (RAM) while being processed, or stored in a non-volatile memory,such as a flash memory, or a Hard Disk Drive (HDD), and then read by theCPU to be modified or rewritten, as necessary.

Note that the apparatuses in the above-described embodiments may bepartially achieved by a computer. In such a case, a program forachieving such control functions may be recorded on a computer-readablerecording medium to cause a computer system to read the program recordedon the recording medium and to perform the program. It is assumed thatthe “computer system” refers to a computer system built into theapparatuses, and the computer system includes an operating system andhardware components such as a peripheral device. Furthermore, the“computer-readable recording medium” may be any of a semiconductorrecording medium, an optical recording medium, a magnetic recordingmedium, and the like.

Moreover, the “computer-readable recording medium” may include a mediumthat dynamically retains a program for a short period of time, such as acommunication line that is used to transmit the program over a networksuch as the Internet or over a communication line such as a telephoneline, and may also include a medium that retains a program for a fixedperiod of time, such as a volatile memory within the computer system forfunctioning as a server or a client in such a case. Furthermore, theabove-described program may be configured to achieve some of thefunctions described above, and additionally may be configured to achievethe functions described above, in combination with a program alreadyrecorded in the computer system.

Furthermore, each functional block or various characteristics of theapparatuses used in the above-described embodiments may be implementedor performed on an electric circuit, that is, typically an integratedcircuit or multiple integrated circuits. An electric circuit designed toperform the functions described in the present specification may includea general-purpose processor, a Digital Signal Processor (DSP), anApplication Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA), or other programmable logic devices, discrete gatesor transistor logic, discrete hardware components, or a combinationthereof. The general-purpose processor may be a microprocessor, or theprocessor may be a processor of known type, a controller, amicro-controller, or a state machine instead. The general-purposeprocessor or the above-mentioned circuits may be configured of a digitalcircuit, or may be configured of an analog circuit. Furthermore, in acase that with advances in semiconductor technology, a circuitintegration technology appears that replaces the present integratedcircuits, it is also possible to use an integrated circuit based on thetechnology.

Supplement

A terminal apparatus according to a first aspect of the presentinvention is a terminal apparatus that supports EN-DC. The terminalapparatus includes a receiver configured to receive an RRC connectionreconfiguration message from a base station apparatus. The RRCconnection reconfiguration message includes a radio bearer identity. Theterminal apparatus further includes a configuration unit configured toestablish a PDCP entity in accordance with a PDCP entity configurationfor NR in a case that the terminal apparatus has not configured a valueof the radio bearer identity and in a case that the RRC connectionreconfiguration message includes the PDCP entity configuration for NR.

A terminal apparatus according to a second aspect of the presentinvention is a terminal apparatus that supports EN-DC. The terminalapparatus includes a receiver configured to receive an RRC connectionreconfiguration message from a base station apparatus. The RRCconnection reconfiguration message includes a radio bearer identity anda PDCP entity configuration corresponding to the radio bearer identity.The PDCP entity configuration is either the PDCP entity configurationfor E-UTRA or the PDCP entity configuration for NR. The terminalapparatus further includes a configuration unit configured to establisha PDCP entity in accordance with the PDCP entity configuration for NR ina case that the terminal apparatus has not configured a value of theradio bearer identity and in a case that the RRC connectionreconfiguration message does not include the PDCP entity configurationfor E-UTRA.

The terminal apparatus according to a third aspect of the presentinvention in the first or the second aspect may be a terminal apparatusin which the PDCP entity corresponds to an MCG bearer of the EN-DC.

A base station apparatus according to a fourth aspect of the presentinvention is a base station apparatus that supports EN-DC. The basestation apparatus includes a generation unit configured to generate anRRC connection reconfiguration message and a transmitter configured totransmit the RRC connection reconfiguration message to a terminalapparatus. The RRC connection reconfiguration message includes a radiobearer identity. The RRC connection reconfiguration message includingthe radio bearer identity causes the terminal apparatus to establish aPDCP entity in accordance with a PDCP entity configuration for NR in acase that the terminal apparatus has not configured a value of the radiobearer identity and in a case that the RRC connection reconfigurationmessage includes the PDCP entity configuration for NR.

A base station apparatus according to a fifth aspect of the presentinvention is a base station apparatus that supports EN-DC. The basestation apparatus includes a generation unit configured to generate anRRC connection reconfiguration message and a transmitter configured totransmit the RRC connection reconfiguration message to a terminalapparatus. The RRC connection reconfiguration message includes a radiobearer identity and a PDCP entity configuration corresponding to theradio bearer identity. The PDCP entity configuration is selected fromthe PDCP entity configuration for E-UTRA and the PDCP entityconfiguration for NR. The RRC connection reconfiguration messageincluding the radio bearer identity and the PDCP entity configurationcauses the terminal apparatus to establish a PDCP entity in accordancewith the PDCP entity configuration for NR in a case that the terminalapparatus has not configured a value of the radio bearer identity and ina case that the RRC connection reconfiguration message does not includethe PDCP entity configuration for E-UTRA.

The base station apparatus according to a sixth aspect of the presentinvention in the fourth or the fifth aspect may be a base stationapparatus in which the PDCP entity corresponds to an MCG bearer of theEN-DC.

A method according to a seventh aspect of the present invention is amethod performed by a terminal apparatus that supports EN-DC. The methodincludes the step of receiving an RRC connection reconfiguration messagefrom a base station apparatus. The RRC connection reconfigurationmessage includes a radio bearer identity. A PDCP entity is establishedin accordance with a PDCP entity configuration for NR in a case that theterminal apparatus has not configured a value of the radio beareridentity and in a case that the RRC connection reconfiguration messageincludes the PDCP entity configuration for NR.

A method according to an eighth aspect of the present invention is amethod performed by a terminal apparatus that supports EN-DC. The methodincludes the step of receiving an RRC connection reconfiguration messagefrom a base station apparatus. The RRC connection reconfigurationmessage includes a radio bearer identity and a PDCP entity configurationcorresponding to the radio bearer identity. The PDCP entityconfiguration is either the PDCP entity configuration for E-UTRA or thePDCP entity configuration for NR. A PDCP entity is established inaccordance with the PDCP entity configuration for NR in a case that theterminal apparatus has not configured a value of the radio beareridentity and in a case that the RRC connection reconfiguration messagedoes not include the PDCP entity configuration for E-UTRA.

The method according to a ninth aspect of the present invention in theseventh or the eighth aspect may be a method in which the PDCP entitycorresponds to an MCG bearer of the EN-DC.

A method according to a tenth aspect of the present invention is amethod performed by a base station apparatus that supports EN-DC. Themethod includes the steps of: generating an RRC connectionreconfiguration message; and transmitting the RRC connectionreconfiguration message to a terminal apparatus. The RRC connectionreconfiguration message includes a radio bearer identity. The RRCconnection reconfiguration message including the radio bearer identitycauses the terminal apparatus to establish a PDCP entity in accordancewith a PDCP entity configuration for NR in a case that the terminalapparatus has not configured a value of the radio bearer identity and ina case that the RRC connection reconfiguration message includes the PDCPentity configuration for NR.

A method according to an eleventh aspect of the present invention is amethod performed by a base station apparatus that supports EN-DC. Themethod includes the steps of: generating an RRC connectionreconfiguration message; and transmitting the RRC connectionreconfiguration message to a terminal apparatus. The RRC connectionreconfiguration message includes a radio bearer identity and a PDCPentity configuration corresponding to the radio bearer identity. ThePDCP entity configuration is selected from the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. The RRC connectionreconfiguration message including the radio bearer identity and the PDCPentity configuration causes the terminal apparatus to establish a PDCPentity in accordance with the PDCP entity configuration for NR in a casethat the terminal apparatus has not configured a value of the radiobearer identity and in a case that the RRC connection reconfigurationmessage does not include the PDCP entity configuration for E-UTRA.

The method according to a twelfth aspect of the present invention in thetenth or the eleventh aspect may be a method in which the PDCP entitycorresponds to an MCG bearer of the EN-DC.

A terminal apparatus according to a thirteenth aspect of the presentinvention is a terminal apparatus for communicating with a base stationapparatus. The terminal apparatus includes a receiver configured toreceive an RRC connection reconfiguration request message including aData Radio Bearer (DRB) configuration from the base station apparatusand a configuration unit configured to configure a DRB in accordancewith the DRB configuration. The DRB configuration includes a DRBidentity and a PDCP entity configuration corresponding to the DRBidentity. A value of the DRB identity is absent in a currentconfiguration of the terminal apparatus, and the PDCP entityconfiguration information includes one of the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. A PDCP entity isestablished in accordance with the PDCP entity configuration informationin a case that the PDCP entity configuration information includesinformation on the PDCP entity configuration for E-UTRA, and the PDCPentity is established in accordance with the PDCP entity configurationinformation in a case that the PDCP entity configuration informationincludes the PDCP entity configuration information for NR.

A terminal apparatus according to a fourteenth aspect of the presentinvention is a terminal apparatus for communicating with a base stationapparatus. The terminal apparatus includes a receiver configured toreceive an RRC connection reconfiguration request message including aData Radio Bearer (DRB) configuration from the base station apparatusand a configuration unit configured to configure a DRB in accordancewith the DRB configuration. The DRB configuration includes a DRBidentity and a PDCP entity configuration corresponding to the DRBidentity. A value of the DRB identity is present in a currentconfiguration of the terminal apparatus, and the PDCP entityconfiguration information includes one of the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. A PDCP entity isreestablished in accordance with the PDCP entity configurationinformation in a case that the PDCP entity configuration informationincludes information on the PDCP entity configuration for E-UTRA, andthe PDCP entity is established in accordance with the PDCP entityconfiguration information in a case that the PDCP entity configurationinformation includes the PDCP entity configuration information for NR.

A terminal apparatus according to a fifteenth aspect of the presentinvention is a terminal apparatus that supports Multi Radio AccessTechnology Dual Connectivity (MR-DC) using Evolved Universal TerrestrialRadio Access (E-UTRA) and New Radio (NR). The terminal apparatusincludes a receiver and a configuration unit. In a case that the E-UTRAis a master cell group, the receiver is configured to receive an RRCconnection reconfiguration request message including a Data Radio Bearer(DRB) configuration of an anchor cell group from a master base stationapparatus, and the configuration unit is configured to configure a DRBin accordance with the DRB configuration. The DRB configuration includesa DRB identity and a PDCP entity configuration corresponding to the DRBidentity. A value of the DRB identity is absent in a currentconfiguration of the terminal apparatus, and the PDCP entityconfiguration information includes one of the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. A PDCP entity isestablished in accordance with the PDCP entity configuration informationin a case that the PDCP entity configuration information includesinformation on the PDCP entity configuration for E-UTRA, and the PDCPentity is established in accordance with the PDCP entity configurationinformation in a case that the PDCP entity configuration informationincludes the PDCP entity configuration information for NR.

A terminal apparatus according to a sixteenth aspect of the presentinvention is a terminal apparatus that supports Multi Radio AccessTechnology Dual Connectivity (MR-DC) using an Evolved UniversalTerrestrial Radio Access (E-UTRA) and a New Radio (NR). The terminalapparatus includes a receiver and a configuration unit. In a case thatthe E-UTRA is a master cell group, the receiver is configured to receivean RRC connection reconfiguration request message including a Data RadioBearer (DRB) configuration of an anchor cell group from a master basestation apparatus, and the configuration unit is configured to configurea DRB in accordance with the DRB configuration. The DRB configurationincludes a DRB identity and a PDCP entity configuration corresponding tothe DRB identity. A value of the DRB identity is present in a currentconfiguration of the terminal apparatus, and the PDCP entityconfiguration information includes one of the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. A PDCP entity isreestablished in accordance with the PDCP entity configurationinformation in a case that the PDCP entity configuration informationincludes information on the PDCP entity configuration for E-UTRA, andthe PDCP entity is reestablished in accordance with the PDCP entityconfiguration information in a case that the PDCP entity configurationinformation includes the PDCP entity configuration information for NR.

The terminal apparatus according to a seventeenth aspect of the presentinvention in the fifteenth or the sixteenth aspect may be a terminalapparatus in which the anchor cell group is a master cell group.

The terminal apparatus according to an eighteenth aspect of the presentinvention in the fifteenth or the sixteenth aspect may be a terminalapparatus in which the anchor cell group is a secondary cell group.

A terminal apparatus according to a nineteenth aspect of the presentinvention is a terminal apparatus that supports Multi Radio AccessTechnology Dual Connectivity (MR-DC) using an Evolved UniversalTerrestrial Radio Access (E-UTRA) and a New Radio (NR). The terminalapparatus includes a receiver and a configuration unit. In a case thatthe E-UTRA is a master cell group, the receiver is configured to receivean RRC connection reconfiguration request message including a Data RadioBearer (DRB) configuration of an anchor cell group and a DRBconfiguration of an additional cell group from a master base stationapparatus, and the configuration unit is configured to configure a DRBin accordance with the DRB configuration. The DRB configuration of theanchor cell group includes a DRB identity of the anchor cell group and aPDCP entity configuration corresponding to the DRB identity of theanchor cell group. The DRB configuration of the additional cell groupincludes the DRB identity of the anchor cell group and information of aDRB type being a split. A PDCP entity of the anchor cell group isreestablished in accordance with PDCP entity configuration informationincluded in the DRB configuration of the anchor cell group correspondingto the DRB identity of the anchor cell group.

The terminal apparatus according to a twentieth aspect of the presentinvention in the nineteenth aspect may be a terminal apparatus in whichthe anchor cell group is a master cell group, and the additional cellgroup is a secondary cell group.

The terminal apparatus according to a twenty-first aspect of the presentinvention in the nineteenth aspect may be a terminal apparatus in whichthe anchor cell group is a secondary cell group, and the additional cellgroup is a master cell group.

The terminal apparatus according to a twenty-second aspect of thepresent invention in any of the thirteenth to the twenty-first aspectsmay be a terminal apparatus in which the PDCP entity configurationinformation includes information indicating a PDCP entity configurationincluding a PDCP sequence number length, and the PDCP sequence numberlength is one or more of integer values including 7.

A terminal apparatus according to a twenty-third aspect of the presentinvention is a terminal apparatus for communicating with a base stationapparatus. The terminal apparatus includes a receiver configured toreceive an RRC connection reconfiguration request message including aData Radio Bearer (DRB) configuration from the base station apparatus,and the configuration unit configured to configure a DRB in accordancewith the DRB configuration. The DRB configuration includes a DRBidentity and a PDCP entity configuration corresponding to the DRBidentity. A value of the DRB identity is absent in a currentconfiguration of the terminal apparatus, and the PDCP entityconfiguration information includes one of the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. A PDCP entity isestablished in accordance with the PDCP entity configuration informationin a case that the PDCP entity configuration information includesinformation on the PDCP entity configuration for E-UTRA, and the PDCPentity is established in accordance with the PDCP entity configurationinformation in a case that the PDCP entity configuration informationincludes the PDCP entity configuration information for NR.

Additionally, a terminal apparatus according to a twenty-fourth aspectof the present invention is a terminal apparatus for communicating witha base station apparatus. The terminal apparatus includes a receiverconfigured to receive an RRC connection reconfiguration request messageincluding a Data Radio Bearer (DRB) configuration from the base stationapparatus, and the configuration unit configured to configure a DRB inaccordance with the DRB configuration. The DRB configuration includes aDRB identity and a PDCP entity configuration corresponding to the DRBidentity. A value of the DRB identity is present in a currentconfiguration of the terminal apparatus, and the PDCP entityconfiguration information includes one of the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. A PDCP entity isreestablished in accordance with the PDCP entity configurationinformation in a case that the PDCP entity configuration informationincludes information on the PDCP entity configuration for E-UTRA, andthe PDCP entity is established in accordance with the PDCP entityconfiguration information in a case that the PDCP entity configurationinformation includes the PDCP entity configuration information for NR.

Additionally, a terminal apparatus according to a twenty-fifth aspect ofthe present invention is a terminal apparatus that supports Multi RadioAccess Technology Dual Connectivity (MR-DC) using Evolved UniversalTerrestrial Radio Access (E-UTRA) and New Radio (NR). The terminalapparatus includes a receiver and a configuration unit. In a case thatthe E-UTRA is a master cell group, the receiver is configured to receivean RRC connection reconfiguration request message including a Data RadioBearer (DRB) configuration of an anchor cell group from a master basestation apparatus, and the configuration unit is configured to configurea DRB in accordance with the DRB configuration. The DRB configurationincludes a DRB identity and a PDCP entity configuration corresponding tothe DRB identity. A value of the DRB identity is absent in a currentconfiguration of the terminal apparatus, and the PDCP entityconfiguration information includes one of the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. A PDCP entity isestablished in accordance with the PDCP entity configuration informationin a case that the PDCP entity configuration information includesinformation on the PDCP entity configuration for E-UTRA, and the PDCPentity is established in accordance with the PDCP entity configurationinformation in a case that the PDCP entity configuration informationincludes the PDCP entity configuration information for NR.

Additionally, a terminal apparatus according to a twenty-sixth aspect ofthe present invention is a terminal apparatus that supports Multi RadioAccess Technology Dual Connectivity (MR-DC) using Evolved UniversalTerrestrial Radio Access (E-UTRA) and New Radio (NR). The terminalapparatus includes a receiver and a configuration unit. In a case thatthe E-UTRA is a master cell group, the receiver is configured to receivean RRC connection reconfiguration request message including a Data RadioBearer (DRB) configuration of an anchor cell group from a master basestation apparatus, and the configuration unit is configured to configurea DRB in accordance with the DRB configuration. The DRB configurationincludes a DRB identity and a PDCP entity configuration corresponding tothe DRB identity. A value of the DRB identity is present in a currentconfiguration of the terminal apparatus, and the PDCP entityconfiguration information includes one of the PDCP entity configurationfor E-UTRA and the PDCP entity configuration for NR. A PDCP entity isreestablished in accordance with the PDCP entity configurationinformation in a case that the PDCP entity configuration informationincludes information on the PDCP entity configuration for E-UTRA, andthe PDCP entity is reestablished in accordance with the PDCP entityconfiguration information in a case that the PDCP entity configurationinformation includes the PDCP entity configuration information for NR.

Additionally, a terminal apparatus according to a twenty-seventh aspectof the present invention is a terminal apparatus that supports MultiRadio Access Technology Dual Connectivity (MR-DC) using an EvolvedUniversal Terrestrial Radio Access (E-UTRA) and a New Radio (NR). Theterminal apparatus includes a receiver and a configuration unit. In acase that the E-UTRA is a master cell group, the receiver is configuredto receive an RRC connection reconfiguration request message including aData Radio Bearer (DRB) configuration of an anchor cell group and a DRBconfiguration of an additional cell group from a master base stationapparatus, and the configuration unit is configured to configure a DRBin accordance with the DRB configuration. The DRB configuration of theanchor cell group includes a DRB identity of the anchor cell group and aPDCP entity configuration corresponding to the DRB identity of theanchor cell group. The DRB configuration of the additional cell groupincludes the DRB identity of the anchor cell group and information of aDRB type being a split. A PDCP entity of the anchor cell group isreestablished in accordance with PDCP entity configuration informationincluded in the DRB configuration of the anchor cell group correspondingto the DRB identity of the anchor cell group.

A terminal apparatus according to a twenty-eighth aspect of the presentinvention is a terminal apparatus for communicating with a base stationapparatus. The terminal apparatus includes a receiver configured toreceive an RRC connection reconfiguration request message including aData Radio Bearer (DRB) configuration from the base station apparatus,and a configuration unit configured to configure a DRB in accordancewith the DRB configuration. The DRB configuration includes a DRBidentity and an SDAP entity configuration corresponding to the DRBidentity. A value of the DRB identity is absent in a currentconfiguration of the terminal apparatus. The SDAP entity configurationincludes an SDAP header length. The SDAP header length is one or more ofinteger values of a multiple of eight including zero. An SDAP entity isestablished in accordance with the SDAP configuration information.

A terminal apparatus according to a twenty-ninth aspect of the presentinvention is a terminal apparatus for communicating with a base stationapparatus. The terminal apparatus includes a receiver configured toreceive an RRC connection reconfiguration request message including aData Radio Bearer (DRB) configuration from the base station apparatus,and a configuration unit configured to configure a DRB in accordancewith the DRB configuration. The DRB configuration includes a DRBidentity and an SDAP entity configuration corresponding to the DRBidentity. A value of the DRB identity is present in a currentconfiguration of the terminal apparatus. The SDAP entity configurationincludes an SDAP header length. The SDAP header length is one or more ofinteger values of a multiple of eight including zero. An SDAP entity isreestablished in accordance with the SDAP configuration information.

These comprehensive or specific aspects may be achieved in a system,apparatus, method, integrated circuit, computer program, or recordingmedium, or may be achieved in any combination of systems, apparatuses,methods, integrated circuits, computer programs, and recording media.

Note that the present invention of the present patent application is notlimited to the above-described embodiments. In the embodiment,apparatuses have been described as an example, but the present inventionof the present application is not limited to these apparatuses, and isapplicable to a terminal apparatus or a communication apparatus of afixed-type or a stationary-type electronic apparatus installed indoorsor outdoors, for example, an AV apparatus, a kitchen apparatus, acleaning or washing machine, an air-conditioning apparatus, officeequipment, a vending machine, and other household apparatuses.

The embodiments of the present invention have been described in detailabove referring to the drawings, but the specific configuration is notlimited to the embodiments and includes, for example, an amendment to adesign that falls within the scope that does not depart from the gist ofthe present invention. Various modifications are possible within thescope of the present invention defined by claims, and embodiments thatare made by suitably combining technical means disclosed according tothe different embodiments are also included in the technical scope ofthe present invention. Furthermore, a configuration in which constituentelements, described in the respective embodiments and having mutuallythe same effects, are substituted for one another is also included inthe technical scope of the present invention.

CROSS-REFERENCE OF RELATED APPLICATION

This application claims the benefit of priority to JP 2017-117492 filedon Jun. 15, 2017, which is incorporated herein by reference in itsentirety.

REFERENCE SIGNS LIST

-   100 E-UTRA-   102 eNB-   104 EPC-   106 NR-   108 gNB-   110 5GC-   112, 114, 116, 118, 120, 124 Interface-   122 UE-   200, 300 PHY-   202, 302 MAC-   204, 304 RLC-   206, 306 PDCP-   208, 308 RRC-   310 SDAP-   500 Receiver-   502 Configuration unit

The invention claimed is:
 1. A terminal apparatus that supports EvolvedUniversal Terrestrial Radio Access New Radio Dual Connectivity,comprising: reception circuitry configured to receive a Radio ResourceControl connection reconfiguration message from a base stationapparatus, the Radio Resource Control connection reconfiguration messageincluding a radio bearer identity; and configuration circuitryconfigured to establish a Packet Data Convergence Protocol entity forNew Radio in accordance with a Packet Data Convergence Protocol entityconfiguration for New Radio, in a case that (a) the radio beareridentity is not a part of a current configuration of the terminalapparatus and (b) the Radio Resource Control connection reconfigurationmessage includes the Packet Data Convergence Protocol entityconfiguration for New Radio, wherein the Packet Data ConvergenceProtocol entity, which is established in accordance with the Packet DataConvergence Protocol entity configuration for New Radio, corresponds toa Master Cell Group bearer for the Evolved Universal Terrestrial RadioAccess New Radio Dual Connectivity.
 2. A terminal apparatus thatsupports Evolved Universal Terrestrial Radio Access New Radio DualConnectivity, comprising: reception circuitry configured to receive aRadio Resource Control connection reconfiguration message from a basestation apparatus, the Radio Resource Control connection reconfigurationmessage including a radio bearer identity and a Packet Data ConvergenceProtocol entity configuration corresponding to the radio beareridentity; and configuration circuitry configured to determine whetherthe received Packet Data Convergence Protocol entity configuration is aPacket Data Convergence Protocol entity configuration for EvolvedUniversal Terrestrial Radio Access or a Packet Data Convergence Protocolentity configuration for New Radio, wherein the configuration circuitryis configured to establish a Packet Data Convergence Protocol entity forNew Radio in accordance with the Packet Data Convergence Protocol entityconfiguration for New Radio, in a case that (a) the radio beareridentity is not a part of a current configuration of the terminalapparatus and (b) the Radio Resource Control connection reconfigurationmessage does not include the Packet Data Convergence Protocol entityconfiguration for Evolved Universal Terrestrial Radio Access, and thePacket Data Convergence Protocol entity, which is established inaccordance with the Packet Data Convergence Protocol entityconfiguration for New Radio, corresponds to a Master Cell Group bearerfor the Evolved Universal Terrestrial Radio Access New Radio DualConnectivity.
 3. A base station apparatus that supports EvolvedUniversal Terrestrial Radio Access New Radio Dual Connectivity,comprising: generation circuitry configured to generate a Radio ResourceControl connection reconfiguration message; and transmission circuitryconfigured to transmit the Radio Resource Control connectionreconfiguration message to a terminal apparatus, wherein the RadioResource Control connection reconfiguration message includes a radiobearer identity, the Radio Resource Control connection reconfigurationmessage including the radio bearer identity causes the terminalapparatus to establish a Packet Data Convergence Protocol entity for NewRadio in accordance with a Packet Data Convergence Protocol entityconfiguration for New Radio, in a case that (a) the radio beareridentity is not a part of a current configuration of the terminalapparatus and (b) the Radio Resource Control connection reconfigurationmessage includes the Packet Data Convergence Protocol entityconfiguration for New Radio, and the Packet Data Convergence Protocolentity, which is established in accordance with the Packet DataConvergence Protocol entity configuration for New Radio, corresponds toa Master Cell Group bearer for the Evolved Universal Terrestrial RadioAccess New Radio Dual Connectivity.
 4. A base station apparatus thatsupports Evolved Universal Terrestrial Radio Access New Radio DualConnectivity, comprising: generation circuitry configured to generate aRadio Resource Control connection reconfiguration message; andtransmission circuitry configured to transmit the Radio Resource Controlconnection reconfiguration message to a terminal apparatus, wherein theRadio Resource Control connection reconfiguration message includes aradio bearer identity and a Packet Data Convergence Protocol entityconfiguration corresponding to the radio bearer identity, the PacketData Convergence Protocol entity configuration is selected from a PacketData Convergence Protocol entity configuration for Evolved UniversalTerrestrial Radio Access and a Packet Data Convergence Protocol entityconfiguration for New Radio, the Radio Resource Control connectionreconfiguration message including the radio bearer identity and thePacket Data Convergence Protocol entity configuration causes theterminal apparatus to establish a Packet Data Convergence Protocolentity for New Radio in accordance with the Packet Data ConvergenceProtocol entity configuration for New Radio, in a case that (a) theradio bearer identity is not a part of a current configuration of theterminal apparatus and (b) the Radio Resource Control connectionreconfiguration message does not include the Packet Data ConvergenceProtocol entity configuration for Evolved Universal Terrestrial RadioAccess, and the Packet Data Convergence Protocol entity, which isestablished in accordance with the Packet Data Convergence Protocolentity configuration for New Radio, corresponds to a Master Cell Groupbearer for the Evolved Universal Terrestrial Radio Access New Radio DualConnectivity.
 5. A method performed by a terminal apparatus thatsupports Evolved Universal Terrestrial Radio Access New Radio DualConnectivity, the method comprising the steps of: receiving a RadioResource Control connection reconfiguration message from a base stationapparatus, the Radio Resource Control connection reconfiguration messageincluding a radio bearer identity; and establishing a Packet DataConvergence Protocol entity for New Radio in accordance with a PacketData Convergence Protocol entity configuration for New Radio, in a casethat (a) the radio bearer identity is not a part of a currentconfiguration of the terminal apparatus and (b) the Radio ResourceControl connection reconfiguration message includes the Packet DataConvergence Protocol entity configuration for New Radio, wherein thePacket Data Convergence Protocol entity, which is established inaccordance with the Packet Data Convergence Protocol entityconfiguration for New Radio, corresponds to a Master Cell Group bearerfor the Evolved Universal Terrestrial Radio Access New Radio DualConnectivity.
 6. A method performed by a terminal apparatus thatsupports Evolved Universal Terrestrial Radio Access New Radio DualConnectivity, the method comprising the steps of: receiving a RadioResource Control connection reconfiguration message from a base stationapparatus, wherein the Radio Resource Control connection reconfigurationmessage includes a radio bearer identity and a Packet Data ConvergenceProtocol entity configuration corresponding to the radio beareridentity; determining whether the received Packet Data ConvergenceProtocol entity configuration is a Packet Data Convergence Protocolentity configuration for Evolved Universal Terrestrial Radio Access or aPacket Data Convergence Protocol entity configuration for New Radio; andestablishing a Packet Data Convergence Protocol entity for New Radio inaccordance with the Packet Data Convergence Protocol entityconfiguration for New Radio, in a case that (a) the radio beareridentity is not a part of a current configuration of the terminalapparatus and (b) the Radio Resource Control connection reconfigurationmessage does not include the Packet Data Convergence Protocol entityconfiguration for Evolved Universal Terrestrial Radio Access, whereinthe Packet Data Convergence Protocol entity, which is established inaccordance with the Packet Data Convergence Protocol entityconfiguration for New Radio, corresponds to a Master Cell Group bearerfor the Evolved Universal Terrestrial Radio Access New Radio DualConnectivity.
 7. A method performed by a base station apparatus thatsupports Evolved Universal Terrestrial Radio Access New Radio DualConnectivity, the method comprising the steps of: generating a RadioResource Control connection reconfiguration message; and transmittingthe Radio Resource Control connection reconfiguration message to aterminal apparatus, wherein the Radio Resource Control connectionreconfiguration message includes a radio bearer identity, the RadioResource Control connection reconfiguration message including the radiobearer identity causes the terminal apparatus to establish a Packet DataConvergence Protocol entity for New Radio in accordance with a PacketData Convergence Protocol entity configuration for New Radio, in a casethat (a) the radio bearer identity is not a part of a currentconfiguration of the terminal apparatus and (b) the Radio ResourceControl connection reconfiguration message includes the Packet DataConvergence Protocol entity configuration for New Radio, and the PacketData Convergence Protocol entity, which is established in accordancewith the Packet Data Convergence Protocol entity configuration for NewRadio, corresponds to a Master Cell Group bearer for the EvolvedUniversal Terrestrial Radio Access New Radio Dual Connectivity.
 8. Amethod performed by a base station apparatus that supports EvolvedUniversal Terrestrial Radio Access New Radio Dual Connectivity, themethod comprising the steps of: generating a Radio Resource Controlconnection reconfiguration message; and transmitting the Radio ResourceControl connection reconfiguration message to a terminal apparatus,wherein the Radio Resource Control connection reconfiguration messageincludes a radio bearer identity and a Packet Data Convergence Protocolentity configuration corresponding to the radio bearer identity, thePacket Data Convergence Protocol entity configuration is selected from aPacket Data Convergence Protocol entity configuration for EvolvedUniversal Terrestrial Radio Access and a Packet Data ConvergenceProtocol entity configuration for New Radio, the Radio Resource Controlconnection reconfiguration message including the radio bearer identityand the Packet Data Convergence Protocol entity configuration causes theterminal apparatus to establish a Packet Data Convergence Protocolentity for New Radio in accordance with the Packet Data ConvergenceProtocol entity configuration for New Radio, in a case that (a) theradio bearer identity is not a part of a current configuration of theterminal apparatus and in (b) the Radio Resource Control connectionreconfiguration message does not include the Packet Data ConvergenceProtocol entity configuration for Evolved Universal Terrestrial RadioAccess, and the Packet Data Convergence Protocol entity, which isestablished in accordance with the Packet Data Convergence Protocolentity configuration for New Radio, corresponds to a Master Cell Groupbearer for the Evolved Universal Terrestrial Radio Access New Radio DualConnectivity.